Jet mills as such are known and are used for the pulverization or disagglomeration of solid particles. A number of older designs are described in detail in U.S. Pat. No. 2,032,827. They customarily comprise a flat, cylindrical pulverizing chamber, in which an inwardly directed circular or spiral flow of a gas or a gaseous fluid transports the particles to be pulverized. Particle comminution or pulverization is essentially achieved by the particles colliding with each other. The energy required for comminution is input via the gaseous medium (propellant), which, in many common configurations, is blown into the pulverizing chamber tangentially through jet nozzles distributed around the circumference, thereby generating and maintaining a vortex. The particles to be pulverized are fed into the pulverizing chamber via a separate feed line. The mills can be installed both horizontally and vertically. The propellant most commonly used is compressed air or steam.
The known jet mills, according to DE 76 17 063 U1, for example, are essentially constructed in such a way that only an inner steel ring is located inside a closed steel casing, comprising a bottom, an outer wall and a cover. The actual pulverizing chamber is located inside the steel ring and is bordered by the steel ring and the corresponding surfaces of the bottom and cover. The propellant is fed into the annular space between the outer casing wall and the inner steel ring, and passed via several nozzles through the inner steel ring into the pulverizing chamber.